1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method and in particular to an image processing apparatus and an image processing method, which can perform image processing to index image data including a plurality of pieces of thumbnail image data.
2. Description of the Related Art
There is a function of arranging thumbnail image data of a plurality of pieces of image data, recorded in storage such as a personal computer, a recorder, a built-in hard disk of a digital television, and a built-in memory of a digital camera, to generate index image data. The thumbnail image data is data obtained by reducing original image data. When the image data recorded in storage is watched on a monitor or a digital television, the image data is retrieved using the index image data of the thumbnail image data, whereby the image data that one wants to watch can be efficiently found.
In order to enhance the display quality of the index image data of the thumbnail image data, there is a technique of applying gamma correction to the index image data based on a statistic value such as an average luminance of the thumbnail image data displayed in the index image data. With this configuration, the display quality can be improved by, for example, increasing contrast of the thumbnail image data displayed in the index image data. Meanwhile, in the gamma correction, for example, when the index image data includes a large amount of thumbnail image data of image data with high luminance, the gamma correction is performed in conformity with the thumbnail image data with high luminance. When the gamma correction is applied to the thumbnail image data with low luminance, black out may occur. Namely, gamma correction processing suitable for the majority of thumbnail image data showing the same gradation tendency may be unsuitable for a minority of thumbnail image data having a gradation tendency different from the gradation tendency of the majority of thumbnail image data. This applies not only to the gamma correction, but also to other image processing such as chromatic correction.
Japanese Patent Application Laid-Open No. 2006-195651 describes a technique of sectionalizing image data into a plurality of areas and performing gradation correction for each area, and the intensity of the correction for the area including an object to be emphasized, such as a face and a person is rendered higher than the intensity of the correction for the area not including the object to be emphasized. With this configuration, it is possible to perform such a correction that in one piece of image data, only a person is emphasized and a background wall and so on are not emphasized.